1. Field of the Invention
The present invention relates to a thin film transistor (TFT) panel, a method of fabricating the same, and an organic light emitting display device (OLED) including the same. More particularly, the present invention relates to a TFT panel having interlayer insulation layers with different dielectric constants in a TFT region and a capacitor region, a method of fabricating the same, and an OLED including the same.
2. Description of the Related Art
In general, an organic light emitting display device (OLED), which is one of flat panel displays, is an emission type display device capable of injecting electrons and holes into an emission layer from an electron injection electrode (cathode) and a hole injection electrode (anode), respectively, to emit light when an exciton, in which the injected electrons are combined with the injected holes, transitions from an excited state to a ground state.
Therefore, unlike liquid crystal displays, there is no need to install a separate light source in the OLED, and it is possible to reduce volume and weight of the display. The OLED can be classified into a passive matrix OLED and an active matrix OLED according to driving mechanism. An active matrix OLED has an active driving element such as a thin film transistor, (TFT), while a passive matrix OLED does not have the active driving element.
While a method of fabricating the passive matrix OLED is simple because of its simple structure, the passive matrix OLED has problems of high power consumption, and has difficulties in realizing a display having a large size screen. In addition, the passive matrix OLED has more interconnections, and therefore reduces the aperture ratio. As a result, the passive matrix OLED is mostly used for small size or lower resolution displays, and an active matrix OLED is used for large size or high resolution displays.
In the case of an active matrix OLED having a TFT panel to drive an organic light emitting diode, the TFT panel includes a TFT and a capacitor. In order to increase the capacitance of the capacitor of the TFT panel, technology to use a high dielectric material for an interlayer insulation layer of the TFT panel has been developed. The high dielectric material, however, increases a parasitic capacitance in the TFT of the TFT panel, and the increased parasitic capacitance of the TFT element degrades the characteristics of the TFT panel, accordingly degrades the quality of the active matrix OLED. Therefore, new technology is necessary to reduce the parasitic capacitance of the TFT of the TFT panel, while maintaining the high capacitance of the capacitor of the TFT panel.